Grizzly bears (Ursus arctos horribilis) are one of the most famous North American mammals, but do you know why they are called that? The grizzly bear is a subspecies of the brown bear. However, although grizzlies are mostly brown, their fur can appear white-tipped or grizzled, which explains their name.

The grizzly bear once lived throughout much of the North American West. Unfortunately, the arrival of Europeans gradually drove it from its original habitat, considerably reducing its population. In 1975, they were listed as threatened under the U.S. Endangered Species Act, and much has been done since then to protect the species. Today, grizzlies can still be found in parts of Wyoming, Montana, Idaho, Washington, and the Alaskan wilderness. They are also one of the most iconic residents of Yellowstone National Park.

Image: Joshua J. Cotten

We all know that wolves are legendary for their eerie howl, but there are many other interesting facts about this peculiar animal. Gray wolves (Canis lupus) are the largest members of the dog family and are native to North America and Eurasia. The size of an adult gray wolf is similar to that of an average dog and it can weigh up to 145 pounds. However, their tracks would outshine those of any dog, as they measure about 5 inches long by 4 inches wide.

Wolves live and hunt in packs of 6 to 10 animals. They are known to travel great distances, even covering 30 miles in a single day. In the United States, gray wolves were hunted to near extinction, although some populations survived and others have since been reintroduced. Today gray wolves can be found in areas such as the Great Lakes states of Minnesota, Wisconsin, and Michigan, the northern Rocky Mountains region, and the northwest.

Image: Yannick Menard

The North American River Otter (Lontra canadensis) is a species of semi-aquatic, carnivorous mammal endemic to the North American continent that can be found along the coasts and rivers of the United States and Canada. Because they are very susceptible to environmental pollution, their population has been reduced considerably in recent years.

It is a mostly nocturnal animal, often seen at dusk or dawn. During the day it takes refuge in burrows with an underwater entrance that leads to a nest chamber lined with plant material and hair. North American River Otters are robust (11 to 31 pounds) and feed on fish and other aquatic prey, such as turtles, frogs, and crabs.

Image: lovelooking

The red fox (Vulpes vulpes) is a species of mammal in the canid family. It is the most abundant fox species in the northern hemisphere and can be found in many national parks across the country. As its name suggests, its fur is reddish in color. The tips of the ears and the ends of the legs, however, are black. They have a bushy tail whose tip is usually white, as is their belly.

Although classified as a carnivore, the red fox is actually an omnivore and, above all, a great opportunist. They are astute, have excellent eyesight, and have a keen sense of smell and hearing. They can hunt prey of a wide variety of sizes, from insects and worms to small mammals, birds, and fish. They also feed on certain vegetables, berries, and fruits.

Image: Jeremy Hynes

The cougar (Puma concolor), also known as the mountain lion, is a mammal native to the Americas. These large, tan cats are found from the Yukon in Canada to the southern Andes Mountains and Patagonia in South America. In the United States, mountain lions can be found mainly in the western part of the country. However, because of their solitary nature and constant threats from humans, it is difficult to estimate exact population numbers.

Mountain lions are slender and agile felines that can adapt to different conditions and environments. They are strict carnivores and have extraordinary vision and acute hearing, which allows them to capture almost any animal, from insects to squirrels, beavers, elk, and deer.

Image: Robert Sachowski

Beavers are known to be one of the only animals that can affect the ecosystem around them, building watertight dams that help preserve water in streams and rivers. The North American beaver (Castor canadensis) is the largest rodent in North America and one of the largest in the world —it can weigh between 24 and 71 pounds! The species is widely distributed throughout the continent, from northern Canada to northern Mexico.

The North American beaver's coat can range from dark brown to reddish brown, and its most distinctive feature, a flattened paddle-shaped tail, allows it to swim. It is perfectly adapted to semi-aquatic life; its ears and nose have valves that close when submerged, and it can close its lips behind its prominent incisors to cut wood underwater.

Image: kidmoses

The Hawaiian Monk Seal (Neomonachus schauinslandi) is a species native to the Hawaiian Islands. With its friendly face and long whiskers, it is perhaps one of the most endearing mammals that can be found in our country. Unfortunately, this seal species is endangered because of the large amount of chemical waste produced by the fishing industry on the reefs and beaches of the northern Pacific Ocean.

The Hawaiian Monk Seal is usually solitary but is always seen accompanied by other specimens. It is known to be piscivorous, that is, it feeds mainly on fish and other marine creatures, such as crustaceans and some species of mollusks. Since it is a predator by nature, when hunting it makes the most of its length (approximately 7 feet) and its large body (between 300 to 600 lb) to catch its prey.

Image: Sebastian Coman Travel

The American red squirrel (Tamiasciurus hudsonicus) lives in the United States and much of Canada. It is a rodent mammal easily recognized for its deep reddish fur, long bushy tail, and prominent lower teeth. It can be differentiated from other North American squirrel species because of its smaller size, 11 to 14 inches.

American red squirrels normally live in the shady areas of coniferous forests and are primarily granivores. They feed on seeds, pine cones, nuts, fruit, and occasionally insects, eggs, and birds. It is mainly active in trees but also swims freely, using its tail as a rudder to change its direction.

Image: Rusty Watson

Elk (Cervus canadensis), also known as wapiti in several Native American cultures, is a species of deer that lives in North America, Central and East Asia. Today, most elk in our country are found primarily in the West, especially in mountainous regions such as Wyoming's National Elk Refuge and Yellowstone National Park. Some eastern states have also reintroduced small herds into natural forest areas.

The most prominent feature of elks is their massive antlers. Each March they shed their antlers, which begin to grow back in May to be ready for the breeding season in late summer. During this time the bellowing of the males echoes through the mountains, announcing the violent battles that serve to decide who mates with whom. The males with the largest antlers, usually the oldest, often win these duels and get to dominate the herd.

Image: Judy Beth Morris

The American bison is a true symbol of American identity. Not only is it the largest mammal in North America, it is also the national mammal of the United States. In addition, it's one of the greatest conservation success stories of all time.

In prehistoric times, there were millions of specimens of American bison (Bison bison) roaming our territory. But by the late 19th century, there were only a few hundred left. Fortunately, thanks to the efforts of several organizations and individuals, the species was reintroduced and today it can be found in a few national parks and reserves as well as in the wild.

Image: Stephen Leonardi